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Dynaudio Acoustics BM5A Compact Monitor

Small and sweet are the new Dynaudio Acoustics BM5A Compact two-way active closefield monitors, and Dynaudio has quite correctly positioned these "babies" as desirable for post and broadcast applications.

Solid, quality small monitors for tight spaces.Small and sweet are the new Dynaudio Acoustics BM5A Compact two-way active closefield monitors, and Dynaudio has quite correctly positioned these “babies” as desirable for post and broadcast applications. I’d agree that they’re a pleasure to have at the workstation because of their compact dimensions: 10.2 inches high x 6.7 inches wide x 9.3 inches deep. At 15.4 pounds apiece, they’re just portable enough to haul around as a key component to a laptop-based audio workstation, and yet big enough to sit comfortably on a console overbridge—or even behind the mix position for 5.1 surround projects.

Features

The BM5A Compact has two driver elements: an Esotec 1.1 inch soft dome tweeter with a 4mm aluminum front dome that uses pure aluminum wire in the voice coil, and a 5.7 inch, one-piece thermoformed polypropylene cone woofer, using a 3-inch pure aluminum voice coil. The published crossover frequency is 1.5 kHz with a 6 dB per octave slope. The monitor uses a bass reflex design, and the rear bass port vent is tuned to 58 Hz. and its published internal enclosure volume is either 4.8 liters or 5 liters, (the volume differing between what’s listed on the Dynaudio Acoustics Web site (www.dynaudioacoustics.com) and in the BM5A Compact’s user’s manual).

The BM5A Compact’s enclosure has the front vertical leading edges sculpted asymmetrically, with respect to vertical, with the narrowest bevel width in-line with the woofer’s center, and the widest bevel width flaring at the top and bottom leading edge. While reducing the plane area affecting the drivers, the varying bevel widths gives a gentle visual illusion that the BM5A Compact has the profile of a barrel.

Dynaudio Acoustics has packed a number of features into the BM5A Compact’s interior; firstly, the twin 50 watt power amplifiers, each feeding its respective driver element through crossover elements and protection circuits, and smartly cooled with a rear panel fin heatsink. The amps have a published response of 55 Hz-21 kHz, ±3 dB, and the manual states an input of –16 dBu RMS will produce a sound pressure level of 85 dB at 1 meter. Maximum peak SPL is delivered with +9 dBu, with the monitor’s input switch set to “0.” But with no input signal applied, the amps are extremely quiet.

Each driver has its own overload protection, whereby the tweeter’s amplifier input is muted if the amp detects current overload to the tweeter, and the woofer’s amplifier applies gain reduction above a certain [unpublished] threshold level – the woofer’s protection circuit also lights a front panel dual-color LED to “orange.” To protect the amplifier itself, a thermo sensor on the heatsink mutes the input and signals the overload by illuminating the same front panel dual-color LED to “red.” The AC power input is fuse protected, and since this is an international product, the operating voltage and fuse value is listed on a small placard near the AC power IEC socket. It’s worth noting there are two power-on green LED indicators, one in front and another in back—a nice feature when adjusting settings, so you’ll always know when the BM5A Compact is on and ready.

Also on the rear panel is the analog balanced input on female XLR, power switch, three-position level input sensitivity slide switch, three-position high pass slide switch, and a trio of three-position slide switches that adjust low, medium, and high frequency response.

The amplifier’s input level can be selected between +4 dB, 0 (unity), or –10 dB to compensate for different console/device level outputs. Dynaudio realized the BM5A Compact physically cannot reproduce very low frequencies and provided the high-pass switch to select between flat, 80 Hz cutoff, or 60 Hz cutoff, so when mating a subwoofer to the BM5A Compact monitors, you can match the cutoff frequency to the sub-woofer. The three switches that affect response are characterized on the Dynaudio web site as “adjustable filters”: The LF switch works below 150 Hz in +2 dB, 0 dB, or –2 dB steps; the MF switch has a 0 dB, -2 dB, or –4 dB selection affecting a center frequency of 450 Hz with a width of 0.7 octave; the HF switch works above 2 kHz in +1 dB, 0 dB, or –1 dB steps.

Dynaudio Acoustics recommends a breaking-in period for the BM5A Compact by playing a CD in repeat mode at medium levels every night for a few days or the first week to soften up the woofer’s rubber gasket before high input levels are applied. The documentation states a supple gasket will make the mid-ranges softer and make more low-end. It’s recommended to perform a one-night break-in period if the monitors haven’t been used for “a month or two.”

In Use

For our actual use, we assigned a pair of BM5A Compacts to several monitoring tasks: a laptop workstation, a QC listening station, a fixed position audio workstation, and control room general monitoring. The task I eagerly anticipated, a QC listening station, was not satisfactory through no fault of the monitors; directly connecting the BM5A Compact to an audio router output makes for a loud room, even with a –10 dB input setting. More promising was the general control room monitoring – in this application, we placed the monitors in the center of the Master Control Room with plenty of air to move and space to fill. As one colleague remarked “They’re nice, and they really give the ‘old college try’ when it comes to reproducing the low frequencies.” As I was carrying the two BM5A Compacts under each arm to another facility, another colleague recognized the monitors from a distance and sidled up, remarking how he liked their accuracy, but lamented their limited low-end response.

The place we really liked the BM 5A Compact was coupled to an audio workstation. We set all controls to ‘flat,’ and lent the monitors to our radio producer spouse to use with her high-end Nuendo laptop workstation, and she liked them so much we had trouble prying them away to complete this review. When she played a linear version and then a high-bitrate MP2 version of an old session recording of The Ben Folds Five, she exclaimed mightily “Aaaah! I can really hear the difference! That’s amazing. Listen to the clarity [in the linear version]!” This was praise indeed from someone who was used to listening closely on quality headphones. At our own desktop workstation, the BM 5A Compact was a welcomed addition; the small footprint meant I could set them at points around an equilateral triangle with 1 meter sides, and still have air- distance from the back and side walls. Because the monitors are not shielded, I kept them over 9 inches from workstation’s CRT video display, and noticed that as they were turned to get at the controls they affected the video monitor’s color and display, effects easily negated by degaussing the video monitor.

Listening to some familiar music, I was impressed with the reproduction detail of the BM5A Compact, and the perceptible depth and musicality they revealed. A listen-angle with the tweeter at ear level, plus or minus a few degrees, produced the best detail. Low SPL and medium SPL were equally accurate, and I preferred the flat EQ setting after auditioning all the other EQ permutations.

Spoken word playbacks had similar accuracy, sibilances were correctly reproduced, and as a low-SPL test I was able to distinguish a page of script being slid against the studio table as the voice talent was reading.